1. Field of the Invention
The present invention relates to a switch gear, and more particularly to an improved multi-position switching actuator for a switch gear which makes it possible to appropriately switch a contact point to another and carry out a 3-position (open-close-earth) control, and a multi-position control by employing a single actuator.
2. Description of the Background Art
In general, a switch gear employs a power distribution system including an overhead power distributing line and a subterranean power distributing line, and allows an electrical power supplied from a first substation to apply to power receiving devices for a plurality of power consumers. Such a switch gear may be used to partition and to branch power lines for the subterranean power lines.
As shown in FIG. 1, the switch gear according to a conventional art includes: a main body 1; four switching actuators 100 respectively disposed at upper portions of the main body 1 and for making a movable contact move; and a plurality of three-phase main bushes 2 disposed at lower portions of the switching actuators 100 and for receiving power from a first substation and supplying or interrupting the power to power receiving facilities of respective electric loads of respective power consumers under the control of the switching actuators 100.
In the conventional switch gear, the switching actuator 100 actuates respective movable contacts of a switching mechanism, the power received from one of the main bushes 2 depending upon its demand, thereby supplying the power to another of the main bushes 2 or to respective power consumers, or interrupting the power supply.
The conventional switching actuator for a switch gear will now be described.
As shown in FIGS. 2-5B, the switching actuator for a switch gear known as a toggle type control device, which carries out a two-position contact switching, includes: a base plate 120; a driving shaft unit 130 disposed at a central portion behind the base plate 120 and having a driving shaft 132 extruded from a marginal end surface thereof; a subordinate driving shaft link unit 140 having a via hole 142 formed through an end portion thereof so that the driving shaft 132 is provided through the via hole 142 for thereby being coupled with the driving shaft unit 130; a spring 150 a left end portion 151 of which is hooked on a protrusion 134 extended backwardly from another end portion of the driving shaft unit 130, and another end portion 15:2 of which is hooked on a protrusion 144 extended from an end portion of the subordinate driving shaft link unit 140; a center shaft unit 160 disposed below a portion at which the driving shaft unit 130 and the subordinate driving shaft link unit 140 are coupled with each other, and an end portion of which is movably engaged to a link 143 which is also movably engaged to the subordinate driving shaft link unit 140; and a control handle 110 disposed at a front portion of the base plate 120 and having an insertion protrusion (not shown) formed at a center thereof so as to be engaged to the driving shaft 132.
The base plate 120 includes a via hole (not shown) formed in a center thereof, and arc openings 121 which are spaced from the via hole (not shown) and are formed on opposite sides of a driving shaft 132.
As shown in FIGS. 4A and 4B, the driving shaft unit 130 includes: a stable arm 131; the driving shaft 132 extended from an end portion of the front surface of the stable arm 131, wherein an insertion opening (not shown) is formed in an end portion of the driving shaft 132 so that a portion extended from the control handle 110 is engaged into the insertion opening (not shown); a limit protrusion 133 extended from an eccentric portion of the front surface of the stable arm 131 for thereby limiting a rotation of the driving shaft unit 130; and the hook protrusion 134 extended from an end portion of a rear surface of the stable arm 131 so as to be rotated in correspondence to the rotation of the driving shaft 132.
In the above driving shaft unit 130, the hook protrusion 134 becomes hooked on the one end portion 151 of the spring 150, and the limit protrusion 133 becomes inserted into the corresponding arc opening 121 formed in the base plate 120, so that the rotation of the driving shaft unit 130 is limited accordingly.
As shown in FIGS. 5A and 5B, the subordinate driving shaft link unit 140 includes: a pair of stable pads 141; a link 143 provided between the pair of stable pads 141; a via hole 142 formed in end portions of the stable pads 141 and for receiving the driving shaft 132 therethrough; an hook protrusion 144 extended from another end portion of a rear surface of the stable pads 141 and being moved by an elastic restoration force of the spring 150; and a limit protrusion 145 extended from a portion of a front surface of the stable pads 141.
Also, in the central portions of the stable pads 141 there is formed an insertion hole which receives an insertion protrusion 146 therethrough.
In the subordinate driving shaft link unit 140, the hook protrusion 144 is hooked on the other end portion 152 of the spring 150, and the limit protrusion 145 is inserted into the arc opening 121 formed in the base plate 120 for thereby limiting the rotation of the subordinate driving shaft link unit 140.
The link 143 includes an insertion opening 143a formed in each end portion thereof. The insertion protrusion 146 of the stable pads 141 and an insertion protrusion 163 extended from a portion of the central shaft unit 160 are correspondingly inserted into the insertion openings 143a, whereby the rotation force of the subordinate driving shaft link unit 140 becomes transferred to the central shaft unit 160.
The central shaft unit 160, as shown in FIG. 2, includes: a center shaft 162; and a stable arm 161 having an insertion protrusion 163 extended from an end portion thereof, wherein the other end of the stable arm 161 is connected to the center shaft 162 and the insertion protrusion 163 is inserted into the insertion opening 143a formed in the link 143.
The operational steps of the conventional contact switching actuator for a switch gear according to the manual control method will now be described with reference to the accompanying drawings.
As shown in FIGS. 6 through 8, when the control handle 110 is gradually rotated in a clockwise direction, the rotational force of the control handle 110 is transferred to the driving shaft unit 130 through the driving shaft 132 connected thereto, and accordingly the driving shaft unit 130 gradually makes a clockwise rotation.
When the driving shaft unit 130 makes its rotation, the hook protrusion 134 formed at the end portion of the rear surface of the driving shaft unit 130 makes its gradual clockwise rotation, thereby causing tension at the spring 150 which is hooked on the hook protrusion 134.
Also, when the limit protrusion 133 of the driving shaft unit 130 is reaches an end portion of the arc opening 121 of the base plate 120 after a continuous rotation of the driving shaft unit 130, the hook protrusion 145 extended from the end portion of the rear surface of the subordinate driving shaft link unit 140 instantly makes an anticlockwise rotation in accordance with an elastic restoration force of the spring 150, whereby the subordinate driving shaft unit 140 instantly makes its counter-clockwise rotation.
When the subordinate driving shaft link unit 140 makes its instant anticlockwise direction, the central shaft 162 which is connected to the link 143 makes also its counter-clockwise rotation, thereby switching a contact coupled to the central shaft 162 to another.
However, although such two-position (open-close) switching operations of the two-position switching actuator for a switch gear may be completely carried out, more than two switching actuators are required in order to satisfy a variety of requirements for such as a 3-position (open-close-earth) contact or a 4-position (open-close-open-close) contact switching.
Consequently, the conventional two-position contact switching actuator results in an inconvenience in its generation as well as causes difficulty in its production as the size of its product becomes larger.